The present invention relates to doors having a pair of skins and an insulating resin core and, more particularly, to the method of making such foam-filled doors.
Doors with metal or plastic skins and insulating foam cores are widely employed at the present time as entry doors because of their insulating characteristics. They are also utilized in interior applications where some sound reducing and heat transfer benefits are sought to be obtained. Doors with metallic skins are also utilized in interior applications where fire resistance is a consideration.
Generally, such foam-filled doors employ not only the skins but also elements forming a peripheral rectangular frame to support the skins. These framing elements comprise stiles and rails, and they may be formed from metal or wood depending upon the characteristics desired. Illustrative of such doors are Multer U.S. Pat. No. 3,512,305 granted May 19, 1970 (metal skins) and Bies et al U.S. Pat. No. 5,239,799 granted Aug. 31, 1993 (synthetic resin skins). In addition, doors in which the skins are formed with opposing flanges which are joined to provide the peripheral frame and a preformed foam core is inserted therebetween are described in Thorn U.S. Pat. No. 4,922,674 granted May 8, 1990.
Heretofore, the prevalent practice has been to assemble the door skins to the peripheral frame and then to inject a foamable synthetic resin composition into the cavity through one or more inlet apertures. This structure is then subjected to heat and pressure in a platen press and the resin expands and cures.
If the door were intended to have a lite or window, the complete door would then be cut to provide the opening for the lite and the lite mounted therein, thus causing the discard of a substantial amount of resin and a secondary operation after forming of the door. To avoid such waste, it has been proposed to form the skins with the lite opening and to provide a dam about the lite opening before the introduction of the resin as described in Governale U.S. Pat. No. 4,327,535 granted May 4, 1982. However, the cost of making and assembling the dam is substantial.
Moreover, the steps of assembling the skins with the frame and inserting the resin into the cavity have generally been manual operations involving substantial labor content, and this has been a significant factor in the cost of such foam-filled doors.
Recently, Applicant's assignee developed a metal skin door employing a continuous metal frame having channels into which flanges on the skins are inserted. This door is the subject of Berghorn et al Application for U.S. application Ser. No. 08/835,143 filed Apr. 4, 1997.
It is an object of the present invention to provide a novel method for manufacturing such foam-filled doors which is conducted in a substantially continuous manner as the components pass through a series of stations on a conveyor system.
It is also an object to provide such a method in which there is close control over the various components as they are being assembled and processed so as to reduce, if not eliminate, manufacturing defects.
Another object is to provide such a method which is relatively economical and requires minimal labor content.
A further object is to provide an installation in which such a method may be practiced efficiently and economically.